This invention relates generally to conveyor systems and more particular to a conveyor system for the baking industry which uses magnetic forces to maintain the conveyed articles on the conveyor system.
In the commercial baking industry, it is necessary to convey the metal dough receptacles as the dough products are proofed and baked. Typically, these metal receptacles are moved along an endless conveyor which extends in helical flights through the particular piece of equipment so that the required residence time of the dough product in the piece of equipment is achieved. The general construction of such endless conveyors is well known and illustrated in the following patents:
______________________________________ Patent No. Patent Date Inventor ______________________________________ 3,094,206 06/18/63 H. H. Stewart, et al 3,285,394 11/15/66 W. E. Lanham, et al 3,440,973 04/29/69 W. E. Lanham, et al 3,478,705 11/18/69 W. E. Lanham, et al 4,726,766 02/23/88 Stewart, et al ______________________________________
Because different sized metal receptacles are used in a typical baking operation, the endless conveyor mounts a plurality of grids thereon that support the pans. Because the pans frequently are moved through arcuate turning movements within the piece of baking equipment, it is also necessary to provide some means for maintaining the metal receptacles on the grids. Several suggestions have been made to maintain the receptacles on the grids. One such technique utilizes a single rib on each grid that extends into depressions in the bottom of the metal receptacle to laterally maintain it in place while another arrangement uses a pair of spaced apart members pivotally mounted on a axis generally parallel to the endless conveyor and spaced laterally thereof so that the unit can accommodate different metal retainer configurations without adjustment. These types of arrangements are illustrated in the following patents:
______________________________________ Patent No. Patent Date Inventor ______________________________________ 4,729,470 03/08/88 Bacigalupe, et al 4,760,911 08/02/88 Bacigalupe, et al ______________________________________
Another arrangement uses a plurality of magnets which are mounted on the grid and magnetically engage the bottoms of the metal receptacles to maintain the receptacle on the grids. This type mechanism is illustrated in U.S. Pat. No. 4,836,360, issued Jun. 6, 1989 to John P. Kasik. One of the problems associated with the magnetic grid arrangement is that the magnitude of the magnetic forces attracting the metal receptacle to the grids is sensitive to the area of contact between the metal receptacle and the magnet. Thus, in order to be economically feasible, it has been necessary to change the numbers and locations of the magnets on the grid each time it was necessary to run metal receptacles of different bottom configurations.